:root {
    --bg: #020617;
    --neon-blue: #0ea5e9;
    --neon-pink: #f43f5e;
    --neon-green: #10b981;
    --text: #f8fafc;
    --glass: rgba(15, 23, 42, 0.8);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    background-color: var(--bg);
    color: var(--text);
    font-family: 'Orbitron', sans-serif;
    overflow: hidden;
    height: 100vh;
}

.arcade-container {
    display: flex;
    flex-direction: column;
    height: 100%;
}

/* Header */
.game-header {
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: rgba(0,0,0,0.5);
    border-bottom: 2px solid var(--neon-blue);
    box-shadow: 0 0 20px rgba(14, 165, 233, 0.3);
}

.back-link {
    color: var(--neon-pink);
    text-decoration: none;
    font-weight: bold;
    text-transform: uppercase;
    font-size: 0.8rem;
    letter-spacing: 2px;
}

.neon-panel {
    background: var(--glass);
    padding: 0.5rem 1.5rem;
    border: 1px solid var(--neon-blue);
    border-radius: 4px;
    display: flex;
    gap: 2rem;
    font-size: 1rem;
    color: var(--neon-blue);
    text-shadow: 0 0 10px var(--neon-blue);
}

/* Stage */
.game-stage {
    flex-grow: 1;
    position: relative;
    background: radial-gradient(circle at center, #1e1b4b 0%, #020617 100%);
}

#pongCanvas {
    width: 100%;
    height: 100%;
}

/* Question HUD */
.hud-center {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background: var(--glass);
    padding: 2rem;
    border-radius: 20px;
    border: 2px solid var(--neon-blue);
    backdrop-filter: blur(10px);
    text-align: center;
    box-shadow: 0 0 40px rgba(14, 165, 233, 0.2);
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    z-index: 50;
}

.formula-display {
    font-size: 3rem;
    font-weight: 900;
    color: #fff;
    text-shadow: 0 0 15px var(--neon-blue);
}

.input-grid {
    display: flex;
    gap: 2rem;
    justify-content: center;
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.input-group label {
    font-size: 0.7rem;
    color: var(--neon-blue);
    letter-spacing: 1px;
}

.input-group input {
    background: rgba(0,0,0,0.5);
    border: 2px solid var(--neon-pink);
    color: #fff;
    width: 80px;
    padding: 0.8rem;
    text-align: center;
    font-family: 'JetBrains Mono', monospace;
    font-size: 1.8rem;
    border-radius: 8px;
    outline: none;
    transition: all 0.3s;
}

.input-group input:focus {
    box-shadow: 0 0 20px var(--neon-pink);
    transform: scale(1.05);
}

/* Overlays */
.overlay {
    position: absolute;
    inset: 0;
    background: rgba(2, 6, 23, 0.95);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 100;
}

.overlay.hidden {
    display: none;
}

.overlay-content {
    text-align: center;
    padding: 3rem;
    border: 3px solid var(--neon-blue);
    border-radius: 30px;
}

.neon-text {
    font-size: 4rem;
    color: var(--neon-blue);
    text-shadow: 0 0 30px var(--neon-blue);
    margin-bottom: 1rem;
}

.best-score-overlay {
    margin: 1.5rem 0;
    font-size: 1.5rem;
    color: var(--neon-green);
    text-shadow: 0 0 10px var(--neon-green);
    font-weight: bold;
}

.btn-neon {
    background: transparent;
    border: 2px solid var(--neon-blue);
    color: var(--neon-blue);
    padding: 1rem 3rem;
    font-size: 1.2rem;
    font-family: 'Orbitron', sans-serif;
    font-weight: bold;
    cursor: pointer;
    margin-top: 2rem;
    transition: all 0.3s;
    border-radius: 5px;
}

.btn-neon:hover {
    background: var(--neon-blue);
    color: #000;
    box-shadow: 0 0 40px var(--neon-blue);
}

.guide {
    margin-top: 2rem;
    text-align: left;
    color: #64748b;
    font-size: 0.9rem;
}

.guide i {
    color: var(--neon-pink);
    margin-right: 0.5rem;
}

/* Input spinners removal */
input::-webkit-outer-spin-button,
input::-webkit-inner-spin-button {
    -webkit-appearance: none;
    margin: 0;
}